D,E D, E\,D,E and F F\,F are points on the circumference of a circle, centre OOO.
Draw on this
Prove that angle DOF=2×angle DEFDOF = 2 \times \text{angle } DEFDOF=2×angle DEF. You must not use any circle theorems in your proof.
19 exam-style questions on AQA GCSE Maths Proof of the Circle Theorems. Each one has a worked solution and a mark scheme showing where the marks go.